Saudi Arabia only concerned with Iran action, not election

Iran's election on Friday is its own concern, regional rival Saudi Arabia said ahead of an "unprecedented" summit between US President Donald Trump and dozens of Muslim nations excluding Iran.

"That's an internal Iranian matter," Saudi Foreign Minister Adel al-Jubeir told journalists when asked his expectations for Friday's presidential vote in Iran.

"When we look at Iran's policy, we don't look at personalities. We look at actions," said Jubeir, repeating allegations about Iran's "aggressive" behaviour in the Middle East.

President Hassan Rouhani faces a tough battle for re-election against hardline cleric Ebrahim Raisi, who has called for a much tougher stance against the West and says a 2015 nuclear deal has not improved the lives of the poor.

It lifted international sanctions in exchange for guarantees that Tehran will not pursue a nuclear weapons capability.

The agreement, between the US under former president Barack Obama, five other world powers, and Tehran, was viewed with suspicion by Riyadh.

Rouhani made the deal a centrepiece of his efforts to end Iran's isolation and rebuild its economy with foreign investment.

"We have seen Iran's record of aggression increase not decrease" since the nuclear pact, Jubeir said, citing the country's support for "terrorism" and efforts to destabilise other countries.

Tehran in turn says Riyadh supports radical Islamist groups.

Jubeir said Trump has been "very clear about the need to push back against Iran."

On Sunday, the US president will join Saudi King Salman and other Muslim leaders for the summit that aims to combat extremism and promote moderation, Jubeir said.

"We believe that this summit is going to focus the world's attention on the need to work together in partnership in order to defeat the scourge of terrorism and the ideology behind it," Jubeir said.

"It's the first of its kind," and shows that both the US and Muslim nations are interested in dialogue and partnership, he said.

"We are expecting to have almost 37 leaders, kings and heads of state. And we expect that we will have six prime ministers and this is an unprecedented level of participation".

Saudi Arabia is part of a US-led military coalition fighting Islamic State in Syria and Iraq.